Boronic acid thrombin inhibitors

A compound selected from boronic acids of formula (I), and pharmaceutically acceptable salts, prodrugs and pharmaceutically acceptable prodrug salts thereof:

• wherein
• X is H (to form NH2) or an amino-protecting group;
• aa1 is an amino acid residue having a side chain selected from formula (A) and (B):
• —(CO)a—(CH2)b-Dc-(CH2)d-E (A)
• —(CO)a—(CH2)b-Dc-Ce(E1)(E2)(E3) (B)
• wherein
• a is 0 or 1;
• e is 1;
• b and d are independently 0 or an integer such that (b+d) is from 0 to 5 or, as the case may be, (b+e) is from 1 to 5;
• c is 0 or 1;
• D is O or S;
• E is a saturated or unsaturated cyclic hydrocarbyl group;
• and
• E1, E2 and E3 are each independently selected from the group consisting of 5-6 membered saturated or unsaturated hydrocarbyl rings, or one of E1, E2 and E3 is hydrogen and the other two are a said hydrocarbyl ring,
• and wherein E, E1, E2 and E3 are halogenated;
• aa2 is a residue of an amino acid which binds to the thrombin S2 subsite;
• and
• R9 is a straight chain alkyl group interrupted by one or more ether linkages and in which the total number of oxygen and carbon atoms is 3, 4, 5 or 6 or R9 is —(CH2)m-W where m is from 2, 3, 4 or 5 and W is —OH or halogen.